Fig 4BCopyright: Reprinted with permission from Elsevier from [doi:10.1006/dbio.1996.0120] Dev Biol 175: 347-57, Avantaggiato V; Acampora D; Tuorto F; Simeone A, Retinoic acid induces stage-specific repatterning of the rostral central nervous system. Copyright 1996